This error is telling you that there is a problem with the connection file to the db that you are using. It is saying that the variables referenced are not valid resources. This usually happens if you have names for these values that do not match up. What are the names of the variables in your connection file that is included on the login page?
If you can please post back with a copy of this page minus the login details so we can take a look. Also, when you try to edit the Authenticate User server behavior what is the result that you get? When you set this up were you using a different connection file?